Peptide Reconstitution Calculator
Mix research peptides with bacteriostatic (BAC) water and know exactly how many insulin syringe units (IU) to draw for your target dose.
Peptide Reconstitution Calculator
Calculate exact bacteriostatic water volume, syringe units (IU), and concentration.
All U-100 syringes share the same scale (1 IU = 0.01 ml). Capacity only limits max pull.
Draw to the 10.0 unit tick on a standard U-100 insulin syringe (1ml = 100 IU).
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The same formula, worked examples for 12 common research compounds, and a unit quick-check table — so you don't have to come back here every time.
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How to Recalculate Your Peptide Dose Correctly
1. Know your vial weight
Confirm the exact milligram (mg) peptide content of your vial — ideally backed by a 3rd-party HPLC/COA test — not the marketing label alone.
2. Add BAC water
Bacteriostatic water (0.9% benzyl alcohol) is standard for reconstitution. The more BAC water you add, the more diluted (and less potent per unit) the solution becomes.
3. Read your syringe units
A standard U-100 insulin syringe holds 100 units = 1 ml. This tool converts your target dose directly to the tick mark to draw — no manual math.
Research Use Only (RUO): Metrics and formulas are provided for laboratory and analytical reference. Nothing on this page is human or clinical dosing advice.
The Reconstitution Formula
The calculator above does this for you, but the arithmetic is worth understanding, because it makes the most common mistake in peptide reconstitution obvious.
Step 1 — Concentration
concentration (mg/ml)
= peptide mass (mg) ÷ BAC water (ml)
A 10 mg vial with 2 ml of bacteriostatic water gives 5 mg/ml, or 5000 mcg/ml.
Step 2 — Syringe units
units (U-100)
= dose (mg) ÷ concentration (mg/ml) × 100
At 5 mg/ml, a 250 mcg dose is 0.25 ÷ 5 × 100 = 5 units.
The mistake almost everyone makes
Adding more bacteriostatic water does not reduce your dose and does not give you more peptide. The mass in the vial was fixed at manufacture. More water simply means a lower concentration, so you draw a larger volume for the same dose. The number of doses in the vial never changes. Water volume controls resolution on the syringe, nothing else.
Worked Examples
Standard reconstitution protocols for commonly researched compounds, with the resulting concentration. Each links to the full compound profile including molecular formula and COA verification steps.
| Compound | Standard reconstitution |
|---|---|
| BPC-157 | 2.5 ml BAC water for 5mg vial (200mcg per 0.1ml) |
| Retatrutide | 2.0 ml BAC water for 10mg vial |
| Tirzepatide | 2.0 ml BAC water for 15mg vial |
| GHK-Cu (Copper Peptide) | 3.0 ml BAC water for 50mg vial |
| Epithalon (Epitalon) | 2.0 ml BAC water for 10mg vial |
Reconstitution volumes are conventions, not requirements. Any volume works provided the concentration is recalculated. See thefull compound databasefor all 34 profiles.
Common Reconstitution Questions
QHow do you know how much BAC water to add to a peptide?
There is no single correct volume, and this trips up nearly everyone starting out. Bacteriostatic water does not change how much peptide is in the vial. It only changes how concentrated the resulting solution is.
Choose the volume that places your intended dose on a comfortably readable part of the syringe. A useful convention is to pick a volume that makes the target dose land on a round number of units. For example, 2 ml into a 10 mg vial gives 5 mg/ml, so a 0.5 mg dose is exactly 10 units.
Two practical limits apply: most vials take 2 to 3 ml comfortably, and reconstituted peptide has a finite in-solution life. Diluting far beyond what will be used inside that window wastes material.
QHow many units is 2 ml of BAC water?
On a U-100 insulin syringe, 1 ml is 100 units, so 2 ml is 200 units. A standard U-100 syringe holds 100 units, so 2 ml is two full draws.
Note that this is total liquid volume, not a dose. What you actually draw depends on concentration: 2 ml into a 10 mg vial produces 5 mg/ml, so 10 units (0.1 ml) contains 0.5 mg of peptide.
QCan you use sterile water instead of bacteriostatic water?
Sterile water for injection contains no preservative, so a vial reconstituted with it has no antimicrobial protection and is effectively single-use. Bacteriostatic water contains 0.9% benzyl alcohol, which suppresses microbial growth and allows the same vial to be used over several days.
There is one case where sterile water is the deliberate choice: compounds with a short documented in-solution stability window, where the protocol is to reconstitute, use immediately, and discard rather than store.
QWhy does my vial not contain what the label says?
Under-filled vials are a documented problem in the research peptide market. Every calculation on this page assumes the stated milligram content is accurate. If a vial labelled 10 mg actually contains 8 mg, every dose drawn is 20 percent below target and no amount of correct arithmetic fixes it.
This is why fill-weight verification matters as much as purity percentage. See ourguide to COA red flagsfor how to check, and thevendor rankingsfor suppliers with batch-linked documentation.
Still Have BAC Water Questions? Keep This PDF Handy.
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